Motor assembly for a push-pull welding torch

ABSTRACT

Motor assemblies and methods for a push-pull torch are disclosed. An example method includes: rotating a mechanical component about a first axis in a welding torch using a drive motor aligned with the first axis; and feeding a welding wire through the welding torch via a first feed roll and a second feed roll, wherein the first feed roll is operatively coupled with the mechanical component, the first and second feed rolls define a plane through which the welding wire passes, and the plane is generally parallel to and offset from the first axis.

BACKGROUND

The invention relates generally to welding systems and, moreparticularly, to a welding torch operable with such systems.

Welding is a process that has increasingly become ubiquitous in variousindustries and applications. While such processes may be automated incertain contexts, a large number of applications continue to exist formanual welding operations. Such welding operations rely on a variety oftypes of equipment to ensure the supply of welding consumables (e.g.,wire feed, shielding gas, etc.) is provided to the weld in anappropriate amount at a desired time. For example, metal inert gas (MIG)welding typically enables formation of a continuous weld bead by feedingwelding wire shielded by inert gas through a welding torch.

The welding torch may include a wire drive assembly to help feed weldingwire through the torch. Such torches are commonly used in applicationsusing aluminum and aluminum alloy wires, which otherwise may not supportthe stresses associated with being pushed from a separate welding wirefeeder to the torch. The wire drive assembly in the torch allows for thewelding wire to be both pushed by a motor in a wire feeder and pulled bya small motor in the torch. Positioning the wire drive assembly in thetorch also allows for efficient control and operation of the wire driveassembly, because an operator is not required to return to the powersource, which may be located hundreds of feet from the welding process,to make adjustments.

During a welding process, the consumable welding wire passes between apair of feed rolls of the wire drive assembly. At least one feed roll isoperated by the motor in the torch to feed the welding wire between thefeed rolls and through the torch. The feed rolls are often separable tofacilitate an initial positioning (e.g., threading) of the welding wirebetween the feed rolls. Unfortunately, it is sometimes difficult tomaintain the feed rolls in a separated position for proper threading ofthe welding wire between the feed rolls. This may cause the welding wireto come out of its desired position between the feed rolls, leading toan inefficient use of time spent rethreading the wire.

In addition, welding wire is generally received into the torch through astructure at the rear of the torch, while the wire drive assembly islocated at an opposite end of the torch. The welding wire may passthrough the length of the torch, between the rear structure and the wiredrive assembly. Unfortunately, constraints on the dimensions of thetorch may lead to a crowded assembly of components between the rearstructure and the wire drive assembly, making it difficult to route thewelding wire through the torch. In addition, the dimension constraintsmay limit the type and relative placement of the motor used to operatethe wire drive assembly.

BRIEF DESCRIPTION

In an exemplary embodiment, a welding system includes a welding torchassembly. The welding torch assembly includes a first feed rollconfigured to rotate about a first axis, a second feed roll disposedopposite the first feed roll about a welding wire feed region, a firsthelical gear coupled to the first feed roll, a second helical gearoperatively coupled to the first helical gear, and a drive motor. Thefirst helical gear is configured to rotate about the first axis, thesecond helical gear is configured to rotate about a second axis torotate the first helical gear about the first axis, wherein the secondaxis is generally perpendicular to the first axis, and the drive motoris configured to rotate the second helical gear about the second axis.The second axis is offset from a plane defined by the welding wire feedregion between the first and second feed rolls.

In another embodiment, a welding torch assembly includes a first feedroll, a second feed roll, a first helical gear, a second helical gear,and a drive motor. The second feed roll is disposed opposite the firstfeed roll about a wire feed plane through which the first and secondfeed rolls direct welding wire. The first helical gear is axiallycoupled with the first feed roll such that a rotation of the firsthelical gear about a first axis rotates the first feed roll about thefirst axis. The second helical gear is engaged with the first helicalgear such that a rotation of the second helical gear about a second axisdrives the rotation of the first helical gear, and the drive motor isconfigured to rotate the second helical gear about the second axis. Thesecond axis is offset from the wire feed plane.

In a further embodiment, a method includes rotating a mechanicalcomponent about a first axis in a welding torch using a drive motoraligned with the first axis. The method also includes feeding a weldingwire through the welding torch via a first feed roll and a second feedroll. The first feed roll is operatively coupled with the mechanicalcomponent, the first and second feed rolls define a plane through whichthe welding wire passes, and the plane is generally parallel to andoffset from the first axis.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of an embodiment of a weldingsystem illustrating a welding torch coupled to a wire feeder;

FIG. 2 is a partial cutaway perspective view of an embodiment of certaincomponents of the welding torch of FIG. 1;

FIG. 3 is an exploded perspective view of an embodiment of components ofthe welding torch of FIG. 1;

FIG. 4 is a perspective view of an embodiment of the welding torch ofFIG. 3 including a curved guide structure;

FIG. 5 is a side view of an embodiment of the welding torch of FIG. 4;

FIG. 6 is a diagrammatical representation of an embodiment of the curvedguide structure of FIG. 4 receiving a welding wire liner;

FIG. 7 is a perspective view of an embodiment of a motor assembly usedin the welding torch of FIG. 3;

FIG. 8 is a rear cutaway view of an embodiment of the welding torch ofFIG. 3 including an offset motor drive;

FIG. 9 is a top view of an embodiment of components of the welding torchof FIG. 8;

FIG. 10 is a perspective view of an embodiment of the welding torch ofFIG. 3 including a lever for maintaining feed rolls in an open position;

FIG. 11 is a rear cutaway view of an embodiment of a wire drive assemblyused in the welding torch of FIG. 10 with the feed rolls in a feedposition;

FIG. 12 is a rear cutaway view of an embodiment of the wire driveassembly of FIG. 11 with the feed rolls in the open position; and

FIG. 13 is a perspective view of an embodiment of the welding torch ofFIG. 3 including a door opened to expose the wire drive assembly.

DETAILED DESCRIPTION

Presently contemplated embodiments are directed toward systems andmethods for operating a welding torch with a motor assembly for rotatingfeed rolls of a wire drive assembly in the torch. The motor assemblyincludes a motor configured to rotate a driving helical gear about afirst axis. The driving helical gear is engaged with a driven helicalgear via threads so that the driving helical gear drives the drivenhelical gear to rotate about a second axis. The first and second axesare perpendicular to each other. The driven helical gear is coupled toone of the feed rolls so that the operation of the motor drives thefeeding of welding wire through the torch. The motor may be offset froma plane defined by the wire feed region through which the welding wiretravels between the feed rolls. The distance of the offset, size andrating of the motor, and/or helical gear ratios may be specificallychosen so that the motor assembly feeds the welding wire at a certainrange of wire feed speeds.

Turning now to the figures, FIG. 1 is an exemplary embodiment of awelding system 10, which includes a power supply 12 and a wire feeder 14coupled to one another via conductors or conduits 16. In the illustratedembodiment, the power supply 12 is separate from the wire feeder 14,such that the wire feeder 14 may be positioned at some distance from thepower supply 12 near a welding location. However, it should beunderstood that the wire feeder 14, in some implementations, may beintegral with the power supply 12. In such cases, the conduits 16 wouldbe internal to the system. In embodiments in which the wire feeder 14 isseparate from the power supply 12, terminals are typically provided onthe power supply 12 and on the wire feeder 14 to allow the conductors orconduits 16 to be coupled to the devices so as to allow for power andgas to be provided to the wire feeder 14 from the power supply 12, andto allow data to be exchanged between the two devices, as described morefully below.

The system 10 is designed to provide wire, power, and shielding gas to awelding torch 18. The torch 18 may be of many different types, andgenerally allows for the feed of a welding wire and shielding gas to alocation adjacent to a workpiece 20, where a weld is to be formed tojoin two or more pieces of metal. A second conductor (not shown) istypically run to the welding workpiece 20 to complete an electricalcircuit between the power supply 12 and the workpiece 20.

The system 10 is designed to allow for data settings to be selected bythe operator, particularly via an operator interface 22 provided on thepower supply 12. The operator interface 22 will typically beincorporated into a front faceplate of the power supply 12, and mayallow for selection of settings such as the type of weld process, thetype of wire to be used, voltage and current settings, and so forth. Inparticular, the system 10 is designed to allow for metal inert gas (MIG)welding with aluminum or other welding wire that is both pushed towardsthe torch 18 and pulled through the torch 18. These weld settings arecommunicated to control circuitry 24 within the power supply 12. Itshould be noted that while reference is made in the present disclosureto “MIG” welding, the torch 18 and techniques described may be used withor without inert gas, such as with flux cored or metal cored wires.

The control circuitry 24 operates to control generation of welding poweroutput that is applied to the welding wire for carrying out the desiredwelding operation. Accordingly, the control circuitry 24 is coupled topower conversion circuitry 26. This power conversion circuitry 26 isadapted to create the output power that will ultimately be applied tothe welding wire at the torch 18. Various power conversion circuits maybe employed, including choppers, boost circuitry, buck circuitry,inverters, converters, and so forth. The power conversion circuitry 26is coupled to a source of electrical power, as indicated by arrow 28.The power applied to the power conversion circuitry 26 may originate inthe power grid, although other sources of power may also be used, suchas power generated by an engine-driven generator, batteries, fuel cellsor other alternative sources. Finally, the power supply 12 illustratedin FIG. 1 includes interface circuitry 30 configured to allow thecontrol circuitry 24 to exchange signals with the wire feeder 14.

The wire feeder 14 includes complimentary interface circuitry 32 that iscoupled to the interface circuitry 30. The wire feeder 14 also includescontrol circuitry 34 coupled to the interface circuitry 32. The controlcircuitry 34 allows for wire feed speeds to be controlled in accordancewith operator selections. The control circuitry 34 is coupled to anoperator interface 36 on the wire feeder 14 that allows selection of oneor more welding parameters, particularly wire feed speed. The operatorinterface 36 also may allow for selection of such weld parameters as thetype of welding process, the type of wire utilized, current, voltage orpower settings, and so forth. The control circuitry 34 is coupled to gascontrol valving 38, which regulates the flow of shielding gas to thetorch 18. In general, such gas is provided at the time of welding, andmay be turned on immediately preceding welding and/or for a short timefollowing welding. The gas supplied to the gas control valving 38 istypically provided in the form of pressurized bottles, as represented inFIG. 1 by arrow 40.

The wire feeder 14 includes components for feeding wire to the weldingtorch 18, and thereby to the welding application, under the control ofcontrol circuitry 34. For example, one or more spools 42 of welding wireare housed in the wire feeder 14. Welding wire 44 is unspooled from thespools 42 and is progressively fed to the torch 18 as described below.Each of the spools 42 may be associated with a clutch 46 that disengagesthe spool 42 when the welding wire 44 is to be fed to the torch 18. Theclutch 46 may be regulated to maintain a minimum friction level to avoidfree spinning of the spool 42. A feed motor 48 is provided that engageswith wire feeder feed rolls 50 to push the welding wire 44 from the wirefeeder 14 towards the torch 18. In practice, one of the feed rolls 50 ismechanically coupled to the feed motor 48 and is rotated by the feedmotor 48 to drive the welding wire 44 from the wire feeder 14, while themating feed roll is biased towards the welding wire 44 to maintain goodcontact between the feed rolls 50 and the welding wire 44. Some systemsmay include multiple rollers of this type. Finally, in certainembodiments, a tachometer 52 is provided for detecting the speed of thefeed motor 48, the feed rolls 50, or any other associated component inorder to provide an indication of the actual wire feed speed. Signalsfrom the tachometer 52 are fed back to the control circuitry 34.

It should be noted that other system arrangements and input schemes maybe implemented. For example, the welding wire 44 may be fed from a bulkstorage container (e.g., a drum) or from one or more spools outside ofthe wire feeder 14. Similarly, the welding wire 44 may be fed from a“spool gun” in which the spool 42 is mounted on or near the weldingtorch 18. As noted herein, the wire feed speed settings may be input viathe operator input 36 on the wire feeder 14, on the operator interface22 of the power supply 12, or both. In systems having wire feed speedadjustments on the torch 18, this may be the input used for the setting.

Power from the power supply 12 is applied to the welding wire 44,typically by means of a weld cable 54. Similarly, shielding gas is fedthrough the wire feeder 14 and the weld cable 54. During weldingoperations, the welding wire 44 is advanced through the weld cablejacket towards the torch 18. Within the torch 18, an additional wiredrive assembly 56 is provided with associated feed rolls, as describedin detail below. The feed rolls contact the welding wire 44 and drivethe welding wire 44 from the wire feeder 14 to a welding application. Atrigger switch 58 within the torch 18 provides a signal that is fed backto the wire feeder 14 and therefrom back to the power supply 12 toenable the welding process to be started and stopped by the operator.That is, upon depression of the trigger switch 58, gas flow is begun,wire is advanced, and power is applied to the weld cable 54 and throughthe torch 18 to the advancing welding wire 44.

FIG. 2 is a partial cutaway perspective view of an embodiment of certaincomponents of the torch 18, which are enclosed in a housing 60. Thesecomponents may include a rear block 62, a feed control assembly 64, amotor 66, one or more conductor tubes 68, a curved guide structure 70,the wire drive assembly 56, and a barrel mount 72. As discussed indetail below, these components facilitate the feeding of consumables(e.g., welding wire 44, electricity, shielding gas) toward a weldingapplication at a desired rate. The illustrated embodiment shows only aportion of the housing 60 that contains these components of the torch18. When the torch 18 is fully assembled, the housing 60 completelyencloses the components and forms a handle through which an operator canmanipulate the torch 18. The housing 60 may be molded plastic or anyother material suitable for holding the torch components. There may bean opening in the housing 60, covered by a door 74. The door 74 may beopened to expose the wire drive assembly 56 as desired. As discussed infurther detail below, the components are arranged in a relativelycompact configuration within the housing 60 to reduce a size and/orweight of the torch 18. This reduction in size and/or weight may benefitwelding operators by increasing maneuverability of the torch 18 anddecreasing the load on the operator.

As outlined above with respect to FIG. 1, the torch 18 enables feedingof the welding wire 44 from the weld cable 54 toward a weldingapplication (e.g., for forming a weld on the workpiece 20). Inparticular, the welding wire 44 enters the torch 18 through an aperturein the rear block 62, passes through the curved guide structure 70, andis fed through the wire drive assembly 56. As mentioned above, thewelding wire 44 may be pushed from a pair of feed rolls 50 in the wirefeeder 14 and simultaneously pulled through the feed rolls in the torch18. The feed rolls of the wire drive assembly 56 exert a compressiveforce on the welding wire 44 and rotate in opposite directions to pullthe welding wire 44 through a welding wire feed region. At certaintimes, it may be desirable for the door 74 to be opened, exposing thewire drive assembly 56 (e.g., during initial threading of the weldingwire 44, servicing or cleaning of the wire drive assembly 56, and soforth). From the wire drive assembly 56, the welding wire 44 passesthrough the barrel mount 72, where it receives an electrical charge.Finally, a nozzle 76 of the torch 18 outputs the charged welding wire 44toward the workpiece 20.

The feed control assembly 64 may adjust a wire feed speed of the weldingwire 44 through the torch 18 based on input from an operator. Forexample, the operator may depress the trigger switch 58 to initiatefeeding of the welding wire 44 through the torch 18, and the operatormay adjust the wire feed speed by turning a dial 78 of the feed controlassembly 64. Thus, the feed control assembly enables one-handed controlof the speed of the welding wire 44 exiting the torch 18.

The torch 18 also outputs shielding gas and electricity to the weldingapplication. The weld cable 54 routes a desired electric current and adesired flow rate of shielding gas from the wire feeder 14 to the torch18, as governed by the control circuitry 24 and 34 of the power supply12 and the wire feeder 14, respectively. The electricity flows into therear block 62 and through the conductor tubes 68 toward the barrel mount72. The rear block 62 is a rear structure of the torch 18 with aperturesformed therein. One of the apertures is for the welding wire 44 to passthrough, while at least one other aperture is for conveying shieldinggas from the weld cable 54 into the hollow conductor tubes 68. The rearblock 62, conductor tubes 68, and barrel mount 72 may each beconstructed from relatively conductive materials (e.g., copper, copperalloys, etc.) and brazed together, minimizing electrical resistancethrough the torch 18. The illustrated embodiment includes two conductortubes 68 for routing the shielding gas and electricity through the torch18. That is, the electricity flows through the structure of theconductor tubes 68, while the shielding gas flows through the hollowportion of the conductor tubes 68. In other embodiments, the conductortubes 68 may convey only the shielding gas without the electricity,which is conveyed by one or more other conductive components of thetorch 18. Other numbers (e.g., 1, 3, 4, etc.) of conductor tubes 68 maybe present in other embodiments, depending on the desired current loadsand/or shielding gas flow rates for the welding application. Forexample, when less current and/or less shielding gas is desired for agiven welding application, the torch 18 may be able to convey thedesired current and gas using a single conductor tube 68. Upon arrivingat the barrel mount 72, the shielding gas flows through the nozzle 76 toshield the weld area throughout the welding process, as described above.The electric current flows from the barrel mount 72 to the welding wire44 as the welding wire 44 exits the torch 18 through the nozzle 76.

FIG. 3 is an exploded perspective view of an embodiment of certaincomponents of the torch 18. These components include the rear block 62,the feed control assembly 64, a motor assembly 102 that includes themotor 66, the conductor tubes 68, the curved guide structure 70, thewire drive assembly 56, and the nozzle 76. The illustrated curved guidestructure 70, motor assembly 102, and wire drive assembly 56 of thetorch 18 may offer benefits over other welding torches used withpush-pull welding systems.

The curved guide structure 70 is configured to guide the welding wire 44between the rear block 62 and the wire drive assembly 56. Morespecifically, the curved guide structure 70 is a continuous structurecoupled between the rear block 62 and the wire drive assembly 56, and isconfigured to guide the welding wire 44 from an aperture 104 in the rearblock 62 to an inlet wire guide 106 of the wire drive assembly 56. Theaperture 104 may be offset relative to the inlet wire guide 106 withrespect to an axial centerline of the torch 18, allowing a relativelysmaller rear block 62 to be used in the torch 18. The smaller rear block62 may contribute to the compactness of the torch design. As a result ofthe offset aperture 104, the welding wire 44 does not follow a straightpath through the torch 18. The curved guide structure 70 is designed toguide the welding wire 44 in a continuous and gently curved mannerbetween the aperture 104 and the inlet wire guide 106, minimizing wearthat occurs on the welding wire 44 as it passes through the torch 18.

The motor assembly 102 powers the rotation of feed rolls in the wiredrive assembly 56 for feeding the welding wire 44 through the torch 18.The wire drive assembly 56 includes a driver feed roll 108 and an idlerfeed roll 110. Both of the feed rolls 108 and 110 are able to rotatewith respect to a body 112 of the wire drive assembly 56. However, thedriver feed roll 108 rotates in response to actuation by the motorassembly 102, while the idler roller 110 rotates freely in response torotation of the driver feed roll 108. The motor assembly 102 rotates thedriver feed roll 108 at an appropriate speed for feeding the weldingwire 44 through the welding torch 18 based on operator input. The motorassembly 102 includes the motor 66, which turns a driving helical gear114. The driving helical gear 114 engages with a driven helical gear116, which is axially coupled to the driver feed roll 108. Thisarrangement allows the motor 66 to drive the rotation of the driver feedroll 108. In presently contemplated embodiments, the motor 66 is alignedlongitudinally with the torch 18, but the motor 66 is offset from aplane defined by the contact area between the feed rolls 108 and 110.The distance of this offset, size and/or rating of the motor 66, gearreduction of the helical gears 114 and 116, and diameter of the driverfeed roll 108 may be adjusted to provide a desired range of wire feedspeeds through the torch 18.

In certain contexts, it may be desirable to separate the feed rolls 108and 110 (e.g., to thread the welding wire 44 therebetween). The wiredrive assembly 56 of the illustrated torch 18 includes a lever 118 thatmay be positioned to separate the feed rolls 108 and 110. Morespecifically, the lever 118 may be positioned to move the idler feedroll 110 away from the driver feed roll 108 and to maintain the idlerfeed roll 110 in an open position. This may enable hands-free separationof the feed rolls 108 and 110 during threading, cleaning, and/oradjusting of the wire drive assembly 56.

In the following discussion, reference may be made to an upstreamlocation or direction and a downstream location or direction. The termsupstream and downstream refer to the direction along a centrallongitudinal axis of the torch 18 through which the welding wire 44passes through the torch 18. That is, the weld cable 54 attaches to therear block 62 at an upstream end of the torch 18 for providing thewelding wire 44 to the torch 18. Likewise, the wire drive assembly 56and the nozzle 76 are located at a downstream end of the torch 18, inorder to feed the welding wire 44 toward a welding application that isstill further downstream.

FIGS. 4-6 illustrate the curved guide structure 70 used to guide thewelding wire 44 through the torch 18. The curved guide structure 70 is acontinuous guide structure, having one inlet and one outlet. Inaddition, the curved guide structure 70 forms a conduit through whichthe welding wire 44 moves between a rear structure (e.g., rear block 62)and a forward structure (e.g., wire drive assembly 56) of the torch 18.As previously described, the rear structure includes a rear structureaperture (e.g., aperture 104) through which the welding wire 44 isreceived, the forward structure includes an aperture (e.g., inlet wireguide 106) through which the welding wire 44 is output, and the curvedguide structure 70 is disposed between and coupled to the rear andforward structure apertures. In embodiments with the wire drive assembly56 in the torch 18, this allows the curved guide structure 70 to routethe welding wire 44 from the aperture 104 to a space between the feedrolls 108 and 110 even when the space is offset from the aperture 104with respect to an axial centerline of the torch 18. The rear structuremay be any structural component of the torch 18 disposed at a relativelyupstream end of the welding torch 18, while the forward structure may beany structural component disposed at a relatively downstream end of thetorch 18. For example, some embodiments of the torch 18 may not includethe wire drive assembly 56 disposed therein, but instead rely on thewire drive assembly (e.g., feed rolls 50) in the wire feeder 14 to pushthe welding wire 44 through the torch 18. In such torches 18, the curvedguide structure 70 may be coupled to the rear block 62 at one end and toa forward structure (e.g., barrel mount 72) located downstream of therear block 62. The torch 18 then outputs the welding wire 44 from thebarrel mount 72 through the nozzle 76 and toward a welding applicationdownstream of the torch 18.

FIG. 4 is a top perspective view of internal components of the torch 18,including the curved guide structure 70. The curved guide structure 70is coupled between the aperture 104 in the rear block 62 and the inletwire guide 106 of the wire drive assembly 56, which aligns the weldingwire 44 with the space between the feed rolls 108 and 110. The rearstructure aperture (e.g., aperture 104) is aligned with a first axis130, the forward structure aperture (e.g., inlet wire guide 106) isaligned with a second axis 136, and the first and second axes 130 and136 are offset from each other. The first axis 130 passes through acenter point 132 of the aperture 104 and extends in a longitudinaldirection 134 of the torch 18. Similarly, the second axis 136 passesthrough the space between the feed rolls 108 and 110 through which thewelding wire 44 passes and extends in the longitudinal direction 134.Indeed, the second axis 136 is aligned with the space between the feedrolls 108 and 110 so that the welding wire 44 may enter the wire driveassembly 56 at a point of tangency to the feed rolls 108 and 110. Inembodiments without the wire drive assembly 56, the second axis 136 maybe aligned with a center point of the barrel mount 72, or some othercomponent that is relatively central to the torch 18.

Since the first axis 130 and the second axis 136 each extend in thelongitudinal direction 134, they are parallel axes. However, the firstand second axes 130 and 136 are offset from each other. The second axis136, defined by the contact area between the feed rolls 108 and 110,does not pass through the center point 132 of the aperture 104. As shownin FIG. 4, a first offset 138 between the first and second axes 130 and136 may be in a horizontal direction 140 relative to the torch 18. Itshould be noted that the horizontal direction 140 is generallyperpendicular to a plane defined by a welding wire feed region (e.g.,the contact area between the feed rolls 108 and 110). FIG. 5, which is aside view of the same components of the torch 18 in FIG. 4, shows asecond offset 142 between the first and second axes 130 and 136 in avertical direction 144 relative to the torch 18. The vertical direction144 is generally parallel to the plane defined by the welding wire feedregion. It should be noted that a first direction may be considered“generally parallel” or “substantially parallel” to a second direction(or plane) when the first direction is within a range of approximately0-5 degrees of the second direction. Similarly, a first direction may beconsidered “generally perpendicular” or “substantially perpendicular” toa second direction (or plane) when the first direction is offset fromthe second direction to within a range of approximately 85-90 degrees

Both of the illustrated horizontal and vertical directions 140 and 144are perpendicular to the longitudinal direction 134. The first andsecond axes 130 and 136 are both substantially parallel to thelongitudinal direction 134 and may be offset from one another in thehorizontal direction 140 and/or the vertical direction 144. That is, thefirst and second axes 130 and 136 may be offset from one another in anydirection substantially perpendicular to the longitudinal direction 134.In FIGS. 4 and 5, the first offset 138 of the first axis 130 relative tothe second axis 136 in the horizontal direction 140 is approximately0.125 inches to the left, and the second offset 142 of the first axis130 relative to the second axis 136 in the vertical direction 144 isapproximately 0.05 inches in the downward direction. In otherembodiments, the first offset 138 and/or the second offset 142 may beany distance less than approximately 0.05, 0.1, 0.5, 1.0, or 1.5 inches.Offsetting the aperture 104 relative to the wire feed region between thefeed rolls 108 and 110 may enable the use of a smaller rear block 62than would be possible using a straight guide structure. Indeed, theaperture 104 may be offset in a horizontal and/or vertical directionthat reduces a horizontal and/or vertical dimension of the rear block62. This may decrease the overall size and weight of the torch 18,making it easier for an operator to manipulate the torch 18.

The curved guide structure 70 is designed to route the welding wire 44from a structure (e.g., rear block 62) at an upstream end 146 of thetorch 18 to a structure at a downstream end 148 of the torch 18. Thecurved guide structure 70 routes the welding wire 44 along a smoothlycurving path between the aperture 104 and the inlet wire guide 106,because of the offsets 138 and 142 in the horizontal and verticaldirections 140 and 144, respectively. In addition, the curved guidestructure 70 has a substantially circular cross sectional area in orderto smoothly convey the welding wire 44, which has a relatively circularcross sectional area. Further, the curved guide structure 70 may begenerally S-shaped to facilitate the smooth feeding of the welding wire44 therethrough, reducing an amount of undesired wear on the weldingwire 44 traveling through the torch 18. For example, the curved guidestructure 70 may include a first slight bend 164 approximately 40% alongthe length of the curved guide structure 70 from the rear block 62, anda second slight bend 165 approximately 70% along the length of thecurved guide structure 70 from the rear block 62. In certainembodiments, the first slight bend 164 may bend the curved guidestructure 70 up in the vertical direction 144 and to the right in thehorizontal direction 140 with respect to the first axis 130 by an angleof approximately 2-5 degrees. In these embodiments, the second slightbend 165 may bend the curved guide structure 70 back by an angle ofapproximately 2-5 degrees toward the second axis 136.

The curved guide structure 70 may be especially useful for holding areplaceable welding wire liner between the offset apertures in the torchstructures. FIG. 6 represents an embodiment of the curved guidestructure 70 receiving a wire liner 160. The wire liner 160 is aflexible conduit designed to offer additional protection of the weldingwire 44 as it passes through the torch 18 and/or the weld cable 54. Incertain embodiments, the wire liner 160 is positioned in the curvedguide structure 70, extending from the rear block 62 to the wire driveassembly 56. In other embodiments, the wire liner 160 is longer andextends through the curved guide structure 70 and through a separateguide structure in the weld cable 54. In this way, the wire liner 160may continuously extend from the wire feeder 14 to the wire driveassembly 56 in the torch 18. The wire liner 160 is made from plastic ora similar material that is flexible, yet rigid enough to be pushedthrough the curved guide structure 70. The wire liner 160 may bereplaceable as it is expected to endure a certain amount of wearthroughout its use. Indeed, over time, the wire liner 160 may becomeclogged with shavings from the outer surface of the welding wire 44.

FIG. 6 shows the insertion of a new wire liner 160 that follows theremoval of an old wire liner during wire liner replacement. The wireliner 160 is inserted through the aperture 104 in the rear block 62 (orother rear structure of the torch 18) as indicated by arrow 162. As thewire liner 160 approaches the bends 164, 165 in the curved guidestructure 70, the wire liner 160 conforms to the shape of the curvedguide structure 70. The wire liner 160 may be secured in place when thewire liner 160 extends to the wire drive assembly 56 from either therear block 62 or the wire feeder 14, depending on the length of the wireliner 160 used. Once the wire liner 160 is in place, the welding wire 44may be inserted through an upstream end 166 of the wire liner 160 andsnaked through the wire liner 160. Once the welding wire 44 is threadedbetween the feed rolls 108 and 110 of the wire drive assembly 56, thewire drive assembly 56 pulls the welding wire 44 through the wire liner160. The wire liner 160 may act as a barrier between the welding wire 44and the curved guide structure 70, or any other structures, in the torch18. In particular, the wire liner 160 may protect the welding wire 44from sharp or hard edges of the curved guide structure 70 and/or variousstructural interfaces or transitions (e.g., between the curved guidestructure 70 and the rear block 62, between the curved guide structure70 and the wire drive assembly 56, and so forth).

FIG. 7 is a perspective view of an embodiment of the motor assembly 102used in the torch 18 of FIG. 3. The motor assembly 102 is configured torotate the driver feed roll 108 about a first axis 170. The first axis170 is substantially parallel to the vertical direction 144 of the torch18. The driver feed roll 108 is disposed opposite the idler feed roll110 across a welding wire feed region, as discussed previously. The twofeed rolls 108 and 110 are configured to advance the welding wire 44through the torch 18. In certain embodiments, the driver feed roll 108may be knurled in order to grip the welding wire 44 effectively, whilethe idler feed roll 110 may include a groove for maintaining thealignment of the welding wire 44 between the feed rolls 108 and 110.

The motor assembly 102 includes the driven helical gear 116, which isaxially coupled with the driver feed roll 108 along the first axis 170.Consequently, the driven helical gear 116 is configured to rotate thedriver feed roll 108 about the first axis 170 as the driven helical gear116 rotates about the first axis 170. The motor assembly 102 alsoincludes the driving helical gear 114, which is operatively coupled withthe driven helical gear 116 and configured to rotate about a second axis172. The second axis 172 is generally parallel to the longitudinaldirection 134 and perpendicular to the first axis 170. The drivenhelical gear 116 is engaged with the driving helical gear 114 such thatrotation of the driving helical gear 114 about the second axis 172causes the driven helical gear 116 to rotate about the first axis 170.

The motor 66, being aligned with the second axis 172, is configured torotate a mechanical component (e.g., the driving helical gear 114 and ashort shaft 176 that couples the driving helical gear 114 to the motor66) about the second axis 172. The mechanical component is operativelycoupled (e.g., via the driven helical gear 116) to the driver feed roll108 so that, in response to the rotation of the mechanical component,the feed rolls 108 and 110 advance the welding wire 44 through the torch18. In the illustrated embodiment, this involves the motor 66 rotatingthe driving helical gear 114, which rotates the driven helical gear 116and the driver feed roll 108. To this end, the motor 66 is configured torotate the short shaft 176 and the coupled driving helical gear 114about the second axis 172. The motor 66 drives a rotation 178 of thedriving helical gear 114 about the second axis 172, which drives arotation 180 of the driven helical gear 116 about the first axis 170.This causes the driver feed roll 108 to rotate about the first axis 170,thereby pulling the welding wire 44 through the wire feed region betweenthe feed rolls 108 and 110. As discussed in further detail below, thesecond axis 172 may be offset from a plane defined by the wire feedregion between the feed rolls 108 and 110.

The helical gears 114 and 116 are rotatably engaged via teeth 174. Inthe illustrated embodiment, the helical gears 114 and 116 are left-handhelical gears, but in other embodiments the helical gears 114 and 116may be right-hand helical gears. The helical gears 114 and 116 should beof the same hand to maintain gear engagement as the helical gears 114and 116 rotate about perpendicular axes 172 and 170. In certainembodiments, there may be the same or a different number of teeth 174 onthe driving helical gear 114 as on the driven helical gear 116. Therelation of the number of teeth 174 on each of the first and secondhelical gears 114 and 116 determines a gear ratio of the helical gears114 and 116. For example, in the illustrated embodiment, the drivinghelical gear 114 has a smaller diameter, and thus fewer teeth 174, thanthe driven helical gear 116. This results in a gear reduction betweenthe helical gears 114 and 116. In other words, the driving helical gear114 makes a full rotation 178 about the second axis 172 in less timethan it takes the driven helical gear 116 to make a full rotation 180about the first axis 170. The rotational speed at which the motor 66turns the driving helical gear 114 is thus reduced to a lower rotationalspeed of the driver feed roll 108. A gear ratio of 1:1.25 between thedriving helical gear 114 and the driven helical gear 116 reduces therotational speed of the driven helical gear 116, and the feed rolls 108and 110, to 80% of the rotational speed output by the motor 66. Thedesired gear ratio of the helical gears 114 and 116 may depend on ashaft speed of the motor 66, a diameter of the driver feed roll 108, anda distance the second axis 172 is offset from a wire feed plane 190.This may determine whether the driving helical gear 114 has fewer, more,or the same number of teeth 174 as the driven helical gear 116.

When helical gears are arranged perpendicularly as shown, one of thegears generates an axial thrust force on the other. The illustratedhelical gears 114 and 116 are arranged such that the driving helicalgear 114 exerts an axial thrust force 182 on the driven helical gear 114in the downward direction with respect to the first axis 170. This isdue to the handedness of the helical gears 114 and 116, the offset ofthe motor 66, and the perpendicular axes 170 and 172. It may bedesirable to arrange the helical gears 114 and 116 in this way so thatthe axial thrust force 182 on the driven helical gear 116 is in thedirection of a support structure (e.g., the body 112 of the wire driveassembly 56). For example, the helical gears 114 and 116 may beconfigured with a certain handedness to facilitate applying the axialthrust force 182 in this direction. When assembled, the illustrateddriver feed roll 108 may be press fit into the body 112 from above. Ifthere is an insufficient press fit between bearings of the drivenhelical gear 116 and the body 112, an axial thrust force in the upwarddirection could lead the driven helical gear 116 and the driver feedroll 108 to lift out of the body 112. However, in the illustratedconfiguration, the downward axial thrust force 182 may draw the drivenhelical gear 116 and the driver feed roll 108 into a desired position inthe body 112 of the wire drive assembly 56.

FIG. 8 is a rear cutaway view of an embodiment of the torch 18 havingthe motor 66 in an offset position. Specifically, the motor 66 is offsetin the horizontal direction 140 from a wire feed plane 190. FIG. 9 is atop view of components of the torch 18, including the motor 66 offsetfrom the wire feed plane 190. The wire feed plane 190 is a plane definedby a welding wire feed region 192 between the feed rolls 108 and 110.That is, the wire feed plane 190 is tangential to the contact areabetween the feed rolls 108 and 110, extending in both the verticaldirection 144 and the longitudinal direction 134. The torch 18 isconfigured to feed the welding wire 44 through the wire feed plane 190between the feed rolls 108 and 110. In the illustrated embodiment, thewire feed plane 190 bisects the torch 18 along its length, forming avertical centerline of the torch 18. The motor assembly 102 may beconfigured so that the second axis 172, along which the motor 66 isaligned, is offset from the wire feed plane 190 in the horizontaldirection 140. The distance of such an offset 194 between the wire feedplane 190 and the second axis 172 may be within a desired range ofapproximately 0.01-1.0 inches, approximately 0.02-0.75 inches,approximately 0.05-0.5 inches, or approximately 0.25 inches. In theillustrated embodiments, the motor 66 is offset horizontally to a firstside (e.g., left) of the wire feed plane 190. This may increase anamount of interior space in the torch 18 on a second side of the wirefeed plane 190 opposite the first side. Other components interior to thetorch 18 may be disposed in the space along the second side. In theillustrated embodiment, for example, the torch 18 is arranged so thatthe conductor tubes 68 are disposed along the second side (e.g., right)of the wire feed plane 190 opposite the first side. In some embodiments,the curved guide structure 70 used to route the welding wire 44 from theaperture 104 to the welding wire feed region 192 may be configured suchthat the aperture 104 is offset from the wire feed plane 190 on thefirst side of the wire feed plane 190. This enables a relativelyefficient use of space within the housing 60, making the torch 18 morecompact. Other embodiments may employ different relative arrangements ofthe motor 66, curved guide structure 70, and conductor tubes 68. Forexample, the motor 66 may be offset on a first side of the wire feedplane 190, while both the aperture 104 is offset on an opposite side ofthe wire feed plane 190 and the conductor tubes are disposed along thefirst side.

It should be noted that the components of the motor assembly 102 in thetorch 18 may be specifically designed to feed the welding wire 44through the torch 18 at a desired range of wire feed speeds. Thedistance of the offset 194, type of motor 66 used, diameter of thedriver feed roll 108, and gear ratio between the helical gears 114 and116 may be specifically tuned to feed the welding wire 44 through thetorch 18 at desired wire feed speeds while maintaining the compactnessof the torch 18. For example, the offset 194 may be greater than thatshown in FIGS. 8 and 9, and the diameter of the driving helical gear 114may be increased to the same diameter as the driven helical gear 116,bringing the gear ratio to 1:1. The resultant range of rotational speedsof the driver feed roll 108 would then be the same as the range ofrotational speeds applicable by the motor 66.

FIG. 10 is a perspective view of an embodiment of components of thetorch 18, including the lever 118 for adjusting a separation between thefeed rolls 108 and 110. As discussed previously, the wire drive assembly56 in the torch 18 is designed to feed the welding wire 44 toward adownstream welding application. The feed rolls 108 and 110 areconfigured to receive the welding wire 44 therebetween and pull thewelding wire 44 through the torch 18. More specifically, the idler feedroll 110 holds the welding wire 44 in a groove 200 formed in the idlerfeed roll 110, and presses the welding wire 44 against the rotatingdriver feed roll 108. In this way, the rotation 180 of the driver feedroll 108 by the motor assembly 102 facilitates the feeding of thewelding wire 44. During this process, the feed rolls 108 and 110 are ina feed position, the feed rolls 108 and 110 being adjacent to and/or incontact with each other.

It may be desirable to selectively move the feed rolls 108 and 110 fromthe feed position to an open position 202, where the feed rolls 108 and110 are separated. The open position 202 of the feed rolls 108 and 110,shown in FIG. 10, enables an operator to thread the welding wire 44 intothe welding wire feed region 192 between the feed rolls 108 and 110.Once the welding wire 44 is properly positioned in alignment with thegroove 200 of the idler feed roll 110, the feed rolls 108 and 110 may berepositioned to the feed position for feeding the welding wire 44through the torch 18. The lever 118 is used to selectively move the feedrolls 108 and 110 between the open position 202 and a feed position 220(e.g., as illustrated in FIG. 11). The lever 118 is also configured tomaintain the feed rolls 108 and 110 in the open position 202 as desiredby the operator. As previously mentioned, the idler feed roll 110 isadjacent to the driver feed roll 108 in the feed position 220, and theidler feed roll 110 is not adjacent to the driver feed roll 108 in theopen position 202. By maintaining the feed rolls 108 and 110 in the openposition 202 as shown, the lever 118 allows the operator to makeadjustments to the welding wire 44, thread the welding wire 44, orservice the wire drive assembly 56 using two hands. This is animprovement over systems in which the operator holds open the feed rolls108 and 110 with one hand while threading the welding wire 44 withanother hand.

In the illustrated embodiment, the lever 118 moves the idler feed roll110 relative to the driver feed roll 108, and the driver feed roll 108is rotatably attached to the body 112. However, this arrangement may bereversed in other embodiments. As previously mentioned, the idler feedroll 110 and the driver feed roll 108 are both configured to rotate withrespect to the body 112 of the wire drive assembly 56. The lever 118 isconfigured to pivot about a lever joint of the body 112 and to maintainthe idler feed roll 110 away from the driver feed roll 108 in responseto the movement of the lever 118. In the illustrated embodiment, thelever joint is a pin 204 extending through the lever 118 and the body112 so the lever 118 can pivot with respect to the body 112. However,any suitable joint mechanism may be used to rotatably couple the lever118 with the body 112. The torch 18 also may include an arm 206 coupledto the idler feed roll 110 and configured to pivot relative to the body112 when urged by the lever 118. FIG. 10 shows the lever 118 urging thearm 206 to pivot relative to the body 112, thereby moving the idler feedroll 110 away from the driver feed roll 108 and into the open position202. In the illustrated embodiment, the arm 206 includes a shelf 208 formaintaining the lever 118 between the arm 206 and the body 112.

FIGS. 11 and 12 are rear cutaway views of an embodiment of the torch 18having the feed rolls 108 and 110 in the feed position 220 and the openposition 202, respectively. The illustrated lever 118 is designed topivot at a first end 222 of the lever 118 about the pin 204 in responseto movement of a second end 224 of the lever 118. The second end 224 iseffectively a handle extending from the first end 222, and this handlemay be raised or lowered to move the idler feed roll 110 between theopen position 202 and the feed position 220. In general, the idler feedroll 110 may only be maintained in either the open position 202 or thefeed position 220 without operator intervention insofar as themechanical features (e.g., of the lever 118, spring 236, and so forth)tend to bias the lever 118 into one of these two positions. Asillustrated in FIG. 11, the spring 236 maintains the idler feed roll 110adjacent the driver feed roll 108 (i.e., in the feed position 220) whenthe second end 224 of the lever 118 is positioned in an orientationsubstantially perpendicular to the welding wire feed region 192. Inother words, the handle of the second end 224 is generally aligned withthe horizontal direction 140 of the torch 18 to maintain the feed rolls108 and 110 in the feed position 220. As shown in FIG. 12, the lever 118maintains the idler feed roll 110 away from the driver feed roll 108(i.e., in the open position 202) when the second end 224 is positionedin an orientation substantially parallel to the welding wire feed region192. That is, the handle of the second end 224 is generally aligned withthe vertical direction 144 of the torch 18. In the illustratedembodiment, the substantially vertical orientation of the second end 224is slightly beyond the vertical direction 144 in the rotationaldirection of arrow 226 (e.g., approximately 100 degrees from thehorizontal direction 140). The orientation of the second end 224relative to the body 112 for maintaining the open position 202 may be anorientation that is offset from first orientation for maintaining thefeed position 220. For example, the second end 224 may be offset (e.g.,arrow 226) from the first orientation along a plane by approximately75-135 degrees, approximately 80-120 degrees, or approximately 90-115degrees. This second orientation of the lever 118 may be offset from thefirst orientation along a plane that is generally defined by thehorizontal and vertical directions 140 and 144 of the torch. That is,the plane in which the lever 118 pivots is substantially perpendicularto the longitudinal direction 134 of the torch.

As previously mentioned, the lever 118 may include a cam surface 228 forurging the arm 206 to pivot relative the body 112 as the lever 118 ispivoted about the pin 204. The cam surface 228 may be shaped such that adistance between the pin 204 and the cam surface 228 changes from oneend of the cam surface 228 to another. In this way, as the lever 118changes orientation with respect to the pin 204, the cam surface 228 mayurge the arm 206 to pivot a greater or lesser distance relative to thebody 112. For example, in the illustrated embodiment the cam surface 228is a distance D1 away from the pin 204 at one end of the cam surface228, and a second distance D2 away from the pin 204 at an opposite endof the cam surface 228. In addition, the cam surface 228 may protrude athird distance D3 from the pin 204 between the first two ends of the camsurface 228. The first distance D1 may be less than the second distanceD2, such that the cam surface 228 urges the arm 206 a greater distanceas the lever 118 rotates about the pin 204. The third distance D3 may begreater than both the first and second distances D1 and D2, such thatthe cam surface 228 keeps the arm 206 from pivoting back once the idlerfeed roll 110 is in the open position 202, as described in detail below.

In order to move the idler feed roll 110 from the feed position 220 tothe open position 202, the lever 118 may be rotated about the pin 204 inthe direction indicated by the arrow 226. As the lever 118 rotates, thecam surface 228 of the lever 118 engages a contact surface 230 of thearm 206. The contact surface 230 is at a first end 232 of the arm 206opposite a second end 234 of the arm 206, and the second end 234 iscoupled to a spring 236. As the lever 118 continues to rotate, the camsurface 228 urges the first end 232 of the arm 206 away from the driverfeed roll 108. The arm 206 pivots about a pin 237 extending through thearm 206 and the body 112 so that the second end 234 moves in a directionthat compresses the spring 236. As the lever 118 rotates still further,the cam surface 228 pivots out of contact with the contact surface 230,and the spring 236 releases a restoring force to move the first end 232of the arm 206 back toward the driver feed roll 108. However, the nowvertically oriented lever 118 stops the arm 206 from pivoting all theway back to its original position. Because of the restoring force of thespring 236 acting on the arm 206, the lever 118 becomes wedged in itsposition between the pin 204 and the arm 206, and may not pivot back tothe horizontal orientation on its own. Thus, the lever 118 maintains thefeed rolls 108 and 110 in the open position 202, without a continuousforce applied by an operator.

To return the feed rolls 108 and 110 to the feed position 220, theoperator may exert a force on the second end 224 of the lever 118 topivot the lever 118 back to the relatively horizontal position.Throughout the rotation of the lever 118, the cam surface 228 urges thefirst end 232 of the arm 206 away from the body 112 slightly beforelosing contact with the contact surface 230. This releases the arm 206to pivot, returning the attached idler feed roll 110 toward the driverfeed roll 108. In addition, it will be appreciated that the spring 236biases the first end 232 of the arm 206 (and, thus, the idler feed roll110) toward the driver feed roll 108. Thus, the spring 236 maintains theidler feed roll 110 in the feed position 220 when the lever ispositioned in the relatively horizontal orientation.

It should be noted that other embodiments may employ other mechanismsfor pivoting a lever to secure the feed rolls 108 and 110 in the openposition 202. However, it is important that torch 18 is designed tomaintain the feed rolls 108 and 110 in the feed position 220 when theextended second end 224 of the lever 118 is positioned in a relativelyhorizontal orientation. This enables a desired level of compactness ofthe wire drive assembly 56 while feeding the welding wire 44 through thetorch 18. FIG. 13 is a perspective view of an embodiment of the torch18, which includes an opening 240 that may be covered by the door 74 ofthe housing 60. The door 74 is opened to expose the wire drive assembly56 (e.g., at least the feed rolls 108 and 110 and the lever 118). In theillustrated embodiment, the lever 118 is configured to block the door 74from closing when the lever 118 holds the idler feed roll 110 in theopen position 202. That is, the lever 118 is positioned in a generallyvertical orientation to maintain the feed rolls 108 and 110 in the openposition 202. In this orientation, the lever 118 may block the door 74from closing over the opening 240. This may keep an operator fromforgetting to disengage the lever 118 from the open position 202 beforeclosing the door 74 and attempting to weld with the torch 18. When thedoor 74 does not close, the operator may return the lever 118 to thegenerally horizontal orientation of the feed position 220 so that thedoor 74 is able to close over the compact wire drive assembly 56.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A method, comprising: rotating a mechanical component about a firstaxis in a welding torch using a drive motor aligned with the first axis;and feeding a welding wire through the welding torch via a first feedroll and a second feed roll, wherein the first feed roll is operativelycoupled with the mechanical component, the first and second feed rollsdefine a plane through which the welding wire passes, and the plane isgenerally parallel to and offset from the first axis.
 2. The method ofclaim 1, wherein rotating the mechanical component comprises rotating afirst helical gear.
 3. The method of claim 2, comprising rotating asecond helical gear axially coupled to the first feed roll based onrotation of the first helical gear, wherein the first and second helicalgears are engaged via teeth.
 4. The method of claim 3, wherein rotatingthe second helical gear comprises rotating the second helical gear abouta second axis that is generally perpendicular to the first axis.
 5. Themethod of claim 4, comprising generating an axial thrust force on thesecond helical gear along the second axis in a direction of a supportstructure of the welding torch.